diff --git a/libisofs/ecma119.c b/libisofs/ecma119.c
index be42733..eb0041a 100644
--- a/libisofs/ecma119.c
+++ b/libisofs/ecma119.c
@@ -1,7 +1,7 @@
 /*
  * Copyright (c) 2007 Vreixo Formoso
  * Copyright (c) 2007 Mario Danic
- * Copyright (c) 2009 - 2012 Thomas Schmitt
+ * Copyright (c) 2009 - 2013 Thomas Schmitt
  *
  * This file is part of the libisofs project; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License version 2 
@@ -1613,7 +1613,8 @@ int checksum_prepare_nodes(Ecma119Image *target, IsoNode *node, int flag)
                  */;
             } else if (ret == 1 && img->checksum_array == NULL) {
                 /* No checksum array loaded. Delete "isofs.cx" */
-                iso_node_set_attrs(node, (size_t) 1,
+                if (!target->will_cancel)
+                  iso_node_set_attrs(node, (size_t) 1,
                               &cx_names, cx_value_lengths, &cx_valuept, 4 | 8);
                 no_md5 = 1;
             } else if (ret == 1 && value_length == 4) {
@@ -1639,8 +1640,9 @@ int checksum_prepare_nodes(Ecma119Image *target, IsoNode *node, int flag)
         }
         /* Equip nodes with provisory isofs.cx numbers: 4 byte, all 0.
            Omit those from old image which will not be copied and have no MD5.
+           Do not alter the nodes if this is only a will_cancel run.
          */
-        if (!no_md5) {
+        if (!(target->will_cancel || no_md5)) {
             ret = iso_file_set_isofscx(file, (unsigned int) 0, 0);
             if (ret < 0)
                 return ret;
diff --git a/libisofs/filesrc.c b/libisofs/filesrc.c
index c3feb8c..654054a 100644
--- a/libisofs/filesrc.c
+++ b/libisofs/filesrc.c
@@ -127,7 +127,7 @@ int iso_file_src_create(Ecma119Image *img, IsoFile *file, IsoFileSrc **src)
     /* insert the filesrc in the tree */
     ret = iso_rbtree_insert(img->files, fsrc, (void**)src);
     if (ret <= 0) {
-        if (ret == 0 && (*src)->checksum_index > 0) {
+        if (ret == 0 && (*src)->checksum_index > 0 && !img->will_cancel) {
             /* Duplicate file source was mapped to previously registered source
             */
             cret = iso_file_set_isofscx(file, (*src)->checksum_index, 0);
@@ -152,7 +152,7 @@ int iso_file_src_create(Ecma119Image *img, IsoFile *file, IsoFileSrc **src)
             no_md5 = 1;
     }
 
-    if ((img->md5_file_checksums & 1) && !no_md5) {
+    if ((img->md5_file_checksums & 1) && !(no_md5 || img->will_cancel)) {
         img->checksum_idx_counter++;
         if (img->checksum_idx_counter < 0x7fffffff) {
             fsrc->checksum_index = img->checksum_idx_counter;
diff --git a/libisofs/md5.c b/libisofs/md5.c
index 7c192a7..cd75eb5 100644
--- a/libisofs/md5.c
+++ b/libisofs/md5.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2009 Thomas Schmitt
+ * Copyright (c) 2009 - 2013 Thomas Schmitt
  *
  * This file is part of the libisofs project; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License version 2 
@@ -527,18 +527,25 @@ int checksum_copy_old_nodes(Ecma119Image *target, IsoNode *node, int flag)
             if (md5_pt == NULL)
                 return 0;
 
-            ret = iso_node_lookup_attr(node, "isofs.cx", &value_length,
-                                       &value, 0);
-            if (ret == 1 && value_length == 4) {
-                for (i = 0; i < 4; i++)
-                    idx = (idx << 8) | ((unsigned char *) value)[i];
-                if (idx > 0 && idx <= target->checksum_idx_counter) {
-                    memcpy(target->checksum_buffer + 16 * idx, md5_pt, 16);
+            if (!target->will_cancel) {
+                ret = iso_node_lookup_attr(node, "isofs.cx", &value_length,
+                                           &value, 0);
+                if (ret == 1 && value_length == 4) {
+                    for (i = 0; i < 4; i++)
+                        idx = (idx << 8) | ((unsigned char *) value)[i];
+                    if (idx > 0 && idx <= target->checksum_idx_counter) {
+                        memcpy(target->checksum_buffer + 16 * idx, md5_pt, 16);
+                    }
                 }
+                if (value != NULL)
+                    free(value);
+
+                /* ts B30114 : It is unclear why these are removed here.
+                               At least with the opts->will_cancel runs,
+                               this is not appropriate.
+                */
+                iso_node_remove_xinfo(node, checksum_md5_xinfo_func);
             }
-            if (value != NULL)
-                free(value);
-            iso_node_remove_xinfo(node, checksum_md5_xinfo_func);
             iso_node_remove_xinfo(node, checksum_cx_xinfo_func);
         }
     } else if (node->type == LIBISO_DIR) {